Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> IMO it was a mistake to turn JIT on in the default config, so that's one
> thing you'll likely want to change.
I wouldn't necessarily go quite that far, but I do think that the
default cost thresholds for invoking it are enormously too low,
or else there are serious bugs in the cost-estimation algorithms
for deciding when to use it. A nearby example[1] of a sub-1-sec
partitioned query that took 30sec after JIT was enabled makes me
wonder if we're accounting correctly for per-partition JIT costs.
regards, tom lane
[1] https://www.postgresql.org/message-id/B6025887-D73F-4B5B-9925-4DA4B675F7E5%40elevated-dev.com
